Final answer:
Crossing over, which happens during prophase I of meiosis, is the process where non-sister chromatids exchange genetic material, resulting in recombinant chromosomes.
Step-by-step explanation:
The recombination that occurs between non-sister chromatids, allowing maternal and paternal homologs to swap segments, is known as crossing over. This happens during prophase I of meiosis, where homologous chromosomes come together and align so precisely that the DNA from one non-sister chromatid can be accurately swapped with the corresponding segment from its homologous non-sister chromatid. This exchange results in recombinant chromosomes that have a mix of maternal and paternal genes, contributing significantly to genetic diversity. Crossing over is essential not only for genetic variation but also for the normal segregation of chromosomes during subsequent phases of meiosis.